1. Field of the Invention
The present invention relates to an exposure apparatus that corrects distortion of an image caused by zigzag movement of a recording stage, which zigzag movement occurs due to movement of the recording stage in exposure processing.
2. Description of the Related Art
Conventionally, as an apparatus in which a predetermined pattern is recorded on a substrate of a recording medium, for example, a printed wiring board (hereinafter referred to as “PWB”) or a flat panel display (hereinafter referred to as “FPD”), a surface exposure apparatus using a mask has been widely used.
However, the fineness of a pattern to be recorded on PWB or FPD (a wiring pattern) becomes higher accompanied by high density packaging of parts, and a problem about displacement of a recording position caused along with expansion and contraction of a mask has become apparent. For example, when a multi-layer printed wiring board is used, alignment of a hole such as a through hole formed on a substrate, and a pattern on each of the layers cannot be carried out with a high degree of accuracy. Accordingly, a problem arises that the fineness of a pattern cannot be made higher.
As a technique provided to solve these problems, there has been known a laser-scanning exposure apparatus in which a pattern is recorded directly on a recording medium, without using a mask, by irradiating a light beam from a recording head. In this laser-scanning exposure apparatus, a pattern can be drawn on a recording medium by carrying out exposure in which light beams are irradiated from multiple recording heads, which are linearly arranged, while moving a recording stage with a recording medium placed thereon.
However, in the aforementioned conventional laser-scanning exposure apparatus, when the recording stage is moved for drawing a pattern on a recording medium, this movement causes zigzag movement of the recording stage and displacement occurs on the recording stage. As a result, there is a problem that distortion is caused in the pattern drawn on the recording medium. The zigzag movement mentioned herein means displacement on the surface of the recording stage in a direction intersecting a direction in which the recording stage moves, which displacement is caused by movement of the recording stage. Due to movement of the recording stage, the surface of the recording stage is displaced in the intersecting direction, and therefore, a position at which a light beam is irradiated from a recording head to the recording medium would be displaced. This zigzag movement has a high reproducibility based on movement of the recording stage, and therefore, it is possible to prepare in advance shift-amount data regarding displacement of the recording stage.
Accordingly, Japanese Patent Application Laid-Open (JP-A) No. 2000-321025 discloses a laser-scanning exposure apparatus in which shift-amount data is prepared in advance by recording the moving behavior of the recording stage using two cameras provided at both sides of the recording stage, and at the time of drawing a pattern on a recording medium, the moving behavior of the recording stage is corrected based on the previously prepared shift-amount data, a light beam is irradiated on the recording medium, thereby allowing a pattern to be drawn thereon.
However, when the recording stage is moved, zigzag movement, which varies delicately at different positions, occurs on the recording stage due to yawing movement (i.e., the behavior of the recording stage in a direction in which it is moved). To this end, a correction amount for correcting zigzag movement varies slightly at respective positions of the recording heads. Accordingly, in order to achieve pattern drawing more precisely, it is necessary to carry out correction by recording the behavior of the recording stage at a greater number of positions and obtaining an amount of displacement at the position of each recording head. However, if the number of cameras used for recording the behavior increases, the manufacturing cost increases.